A211081 1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, one or two horizontal and vertical neighbors

1, 16, 936, 210780, 181263453, 596226368451, 7500390386674716, 360860802332072507724, 66401649279259441073029473, 46730621582712339208520777565573

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..11

Example

Some solutions for n=4
..0..2..1..3....2..2..3..3....2..2..3..3....2..0..1..2....2..0..3..2
..2..0..0..2....2..0..2..1....2..0..3..3....0..0..2..3....0..2..1..0
..1..0..0..1....3..2..1..3....3..3..2..1....1..2..1..1....3..1..3..2
..3..2..1..0....3..1..3..1....3..3..1..3....2..3..1..0....2..0..2..3

Crossrefs

Sequence in context: A173953 A211105 A276637 * A197449 A264640 A211086

Adjacent sequences: A211078 A211079 A211080 * A211082 A211083 A211084

Keyword

nonn

Author

R. H. Hardin Mar 31 2012

Status

approved